Bacterial resistance to [unreadable]-lactam antibiotics is primarily conferred by [unreadable]-lactamases, which render the antibiotic ineffective by hydrolyzing the [unreadable]-lactam C-N bond. The rapid emergence and spread of drug resistant strains pose a serious public health threat. The situation is potential disastrous for pathogenic microorganisms that can acquire resistance through (class B) metallo-[unreadable]-lactamases, which have a broad substrate profile and no clinically useful inhibitor. As a result, there is an urgent desire to understand the catalytic mechanism of metallo-[unreadable]-lactamases, which may help the rational design of effective inhibitors. This small-grant proposal describes a focused and self-contained research plan to elucidate the substrate binding and catalysis of a subclass B2 [unreadable]-lactamase, which primarily catalyzes the hydrolysis of carbapenems with a single zinc cofactor. This research project is motivated by a recent breakthrough in structural determination of the [unreadable]-lactamase CphA from A. hydrophila and its complex with an reaction intermediate, which provide a rare opportunity and excellent starting point for computational simulations of substrate binding and catalysis. The proposed research includes docking and simulations of the enzyme-antibiotic complex, and theoretical studies of catalysis mechanism, using a highly efficient and reasonably accurate quantum mechanical/molecular mechanical approach. Some preliminary results have been obtained and are very encouraging. This research is expected to greatly advance our understanding of the antibiotic binding pattern and catalytic mechanism of subclass B2 metallo-[unreadable]-lactamases, yielding valuable insights into their structure-function relationship. It will also pave the way for more extensive studies of other metallo-[unreadable]- lactamases and possible collaborations with experimentalists. The proposed research is fundamental in nature, but will impact public health by providing a solid foundation for designing novel and effective drugs to combat bacterial infections. [unreadable] [unreadable] [unreadable]